> ## Documentation Index
> Fetch the complete documentation index at: https://docs.taprails.xyz/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Welcome to the TapRails Developer Hub. Stablecoin NFC payment infrastructure for fintechs and neobanks.

<img className="block dark:hidden" src="https://mintlify.s3.us-west-1.amazonaws.com/taprails/images/hero-light.png" alt="TapRails Hero" />

TapRails is a B2B payment infrastructure layer that enables stablecoin tap-to-pay inside your existing product. We provide the APIs, SDKs, and settlement rails — you own the user experience.

Today, a user on Phantom can't tap-to-pay a merchant on Coinbase. A customer on Trust Wallet can't settle with a vendor on KAST. Every wallet is an island.

**TapRails fixes this.**

We are the interoperability layer for stablecoin tap-to-pay — the rails that sit between wallets, apps, and payment terminals so that any sender can pay any receiver, regardless of what wallet either party is using. One tap. Any wallet. Settled on-chain.

For fintechs, neobanks, and crypto wallets, TapRails is the infrastructure you embed to make this possible inside your product — without building settlement, NFC handling, or cross-wallet routing yourself.

<Info>
  **The TapRails idea in one sentence:** Pay from any wallet. Receive into any wallet. TapRails handles the bridge.
</Info>

## The interoperability problem

<CardGroup cols={2}>
  <Card title="Without TapRails" icon="xmark">
    A customer on Phantom wants to tap-to-pay at a merchant using Coinbase. The wallets don't speak to each other. The payment fails. The merchant loses the sale.
  </Card>

  <Card title="With TapRails" icon="check">
    The customer taps their phone. TapRails routes and settles the payment on Base — wallet-agnostic, near-instant. The merchant receives funds into their wallet of choice. Neither party notices the bridge.
  </Card>
</CardGroup>

## Who TapRails is for

TapRails is a B2B infrastructure product. We don't serve merchants or consumers directly — we power the products that do.

<CardGroup cols={3}>
  <Card title="Fintechs" icon="building-columns">
    Embed wallet-agnostic stablecoin NFC payments into your app without building cross-wallet settlement from scratch.
  </Card>

  <Card title="Neobanks" icon="credit-card">
    Offer your users a modern, borderless payment rail that settles in stablecoins on Base.
  </Card>

  <Card title="Crypto Wallets" icon="wallet">
    Let your users spend their stablecoin balance in the real world with a single tap.
  </Card>
</CardGroup>

## How it works

TapRails uses **Host Card Emulation (HCE)** to turn a customer's Android phone into an NFC payment instrument. Our infrastructure handles cross-wallet routing and settles every transaction on Base (Coinbase's L2) (We are chain agnostic, but Base is the available chain for now).

<Steps>
  <Step title="Customer taps their phone">
    Your app, powered by the TapRails SDK, emulates an NFC card using a unique partner AID (typically starting with `F0`). The customer taps their phone at the merchant's NFC reader — regardless of which wallet the merchant uses.
  </Step>

  <Step title="TapRails bridges the wallets">
    TapRails routes the payment between sender and receiver wallets, abstracting away wallet-specific protocols. Phantom to Coinbase. Trust Wallet to KAST. Gnosis Pay to Revolut. It doesn't matter.
  </Step>

  <Step title="Settlement on Base">
    The transaction settles on Base using our pre-funded pool model or our session key model — near-instant, low-cost, and fully on-chain. Both parties settle in their stablecoin of choice.
  </Step>
</Steps>

## What you can build

<CardGroup cols={2}>
  <Card title="Cross-wallet tap-to-pay" icon="nfc" href="/guides/tap-to-pay">
    Let your users pay any merchant, on any wallet, with a single tap.
  </Card>

  <Card title="Merchant acceptance" icon="store" href="/guides/merchant-acceptance">
    Turn any Android phone into a stablecoin POS terminal that accepts payments from any wallet.
  </Card>

  <Card title="Cross-border spend" icon="globe" href="/guides/cross-border">
    Enable stablecoin payroll recipients to spend locally at point of sale — across wallets, across borders.
  </Card>

  <Card title="Wallet-native interoperability" icon="arrow-right-arrow-left" href="/guides/wallet-integration">
    Embed cross-wallet NFC payments directly inside your crypto wallet without redirecting users.
  </Card>
</CardGroup>

## Key Features

<CardGroup cols={2}>
  <Card title="NFC Tap-to-Pay" icon="nfc" color="#7C3AED">
    Full HCE (Host Card Emulation) for merchant devices and NFC reading for customer devices.
  </Card>

  <Card title="Two Payment Modes" icon="wallet" color="#7C3AED">
    **POOL** (custodial, your company wallet) or **SESSION\_KEY** (non-custodial, user's own wallet).
  </Card>

  <Card title="Built-in UI" icon="paintbrush" color="#7C3AED">
    Complete payment flow screens with TapRails branding, 60fps animations, and full accessibility support.
  </Card>

  <Card title="Secure by Default" icon="shield-check" color="#7C3AED">
    ECDSA-signed NFC invoices, replay-attack protection, device Keychain key storage.
  </Card>

  <Card title="Zero-App Fallback" icon="browser" color="#7C3AED">
    Dual-path NFC flow: integrated apps use primary HCE, while others fall back to a secure web payment experience.
  </Card>
</CardGroup>

## SDKs

<CardGroup cols={3}>
  <Card title="React Native" icon="react" color="#61DAFB" href="/get-started">
    Available Now (`@taprails/tap-to-pay`)
  </Card>

  <Card title="Flutter" icon="crow" color="#02569B">
    Coming Soon
  </Card>

  <Card title="Android (Java/Kotlin)" icon="android" color="#3DDC84">
    Coming Soon
  </Card>

  <Card title="iOS (Swift)" icon="apple" color="#F05138">
    Coming Soon
  </Card>
</CardGroup>

## Platform Support

Regardless of the framework used, the following device capabilities are required:

| Role                          | iOS       | Android        |
| ----------------------------- | --------- | -------------- |
| **Customer** (Integrated App) | ✅ iOS 13+ | ✅ Android 5.0+ |
| **Customer** (Web Fallback)   | ✅ iOS 13+ | ✅ Android 5.0+ |
| **Merchant** (HCE emitter)    | ❌         | ✅ Android 5.0+ |

<Warning>
  **iOS cannot act as a merchant (HCE emitter).** Apple restricts Host Card Emulation to Apple Pay only. The device accepting payment (merchant terminal) **must be Android**. However, the customer paying can be on **any device** — integrated apps use the native HCE path, while others use the secure web fallback.
</Warning>

## Next Steps

<CardGroup cols={2}>
  <Card title="Get Started" icon="bolt" href="/get-started">
    Get your API keys and make your first cross-wallet payment in under 15 minutes.
  </Card>

  <Card title="Installation" icon="download" href="/installation/overview">
    Full setup guide for iOS and Android.
  </Card>
</CardGroup>